Exertional heatstroke — DTM&H MCQ

Correct answer: A — Immediate aggressive external cooling and IV normal saline

The correct answer is A, immediate aggressive external cooling and IV normal saline. This presentation, a core temperature of 41.2C, altered consciousness and anhidrosis (dry hot skin) in a young worker exposed to extreme heat, is classic exertional heatstroke, a medical emergency with high mortality if cooling is delayed. Anhidrosis signals failure of thermoregulatory sweating, meaning the body cannot self correct and external cooling (cold water immersion, evaporative fans with water spray, ice packs to groin/axillae/neck) must be started within minutes, aiming to bring core temperature below 39C as rapidly as possible. IV normal saline simultaneously corrects volume depletion and supports circulation while cooling proceeds; cooling and fluids are given together, not sequentially, because rapid cooling is the single intervention proven to reduce mortality and organ damage (rhabdomyolysis, acute kidney injury, DIC, hepatic failure). Why the other options are wrong: C. Oral rehydration with electrolyte solution: the patient has altered consciousness, so oral intake risks aspiration, and oral fluids cannot address the immediate life-threatening hyperthermia. E. Cold IV fluids alone: IV fluids correct hypovolaemia but cold IV fluids alone are far too slow to reduce core temperature at the required rate and do not substitute for external cooling. B. Paracetamol for temperature reduction: heatstroke hyperthermia is caused by failed heat dissipation, not hypothalamic pyrogen resetting, so antipyretics are pharmacologically ineffective and can worsen hepatic injury in a patient already at risk of liver failure. D. Gradual passive cooling with shade and fan: passive measures are too slow for a core temperature above 41C with CNS involvement; delay of aggressive cooling directly increases mortality and end organ damage. Key point: In heatstroke with CNS dysfunction and anhidrosis, survival depends on immediate, aggressive active cooling started simultaneously with IV fluid resuscitation, not on antipyretics or slow passive measures.

Reference: UK Health Security Agency, Adverse Weather and Health Plan: supporting guidance on heat-related illness recognition and management, 2023, https://www.gov.uk/government/publications/adverse-weather-and-health-plan